In continuation of a project on the chemical fine structure of lung heparinoid polysaccharides, techniques have been developed for isolation and structural diagnosis of fragments derivable from degradation and further chemical manipulation. Reference di- and tetrasaccharides have been prepared and characterized. Present efforts center on obtaining characterized trisaccharides. In addition to chemical methods, the use of specific hydrolases is being exploited for both production and characterization of desired fragments. For this purpose, a partial purification of beef liver alpha-L-iduronidase has been effected, partial purification of sulfoiduronate sulfatase is in work, and use of other enzymes will be explored.